L1a

Question 1

Crown definition:

Answer 1

• An artificial replacement that restores missing tooth structure by surrounding part or all of the remaining structure with a material such as cast metal, porcelain, or a combination of materials such as metal and porcelain

Question 2

Indications for crowns:

Answer 2

• Protection of the remaining tooth structure (teeth can be sufficiently weakened through extensive caries, large restorations, extensive wear, endodontic treatment, presence of cracks)
• Alteration of Aesthetics
• Alteration of crown form to facilitate the construction of removable partial dentures (act as abutments)
• To alter the occlusal plane

Question 3

Types of crown:

Answer 3

• All Ceramic Crown
• Ceramo-metal Crown
• Full gold crown
• Partial Coverage crown
• Zirconia crown (monolithic)

Question 4

Most commonly used material:

Answer 4

• Lithium Disilicate (E-max)

Question 5

Advantages and disadvantages of All ceramic crown:

Answer 5

Advantages:

• Excellent Aesthetics
• Preservation of tooth structure in some areas

Disadvantages:

• Increased destruction of tooth structure in some areas
• Longevity?
• Moderate strength
• Abrasive to opposing teeth

Question 6

advantages and disadvantages of Ceramo-metal crown:

Answer 6

Advantages:

• Good Aesthetics
• Longevity
• Preservation of tooth structure in some areas

Disadvantages:

• Increase destruction of tooth structure in some areas

Question 7

advantages and disadvantages of Full Gold Crown:

Answer 7

Advantages:

• Control and stability of occlusion (kind to opposing teeth)
• Longevity
• Maximal preservation of tooth structure

Disadvantages:

• Poor aesthetics
• Can be expensive these days

Question 8

advantages and disadvantages of partial coverage:

Answer 8

Advantages:

• Good aesthetics
• Longevity
• Preservation of tooth structure

Disadvantages:

• Complicated to prepare and to manufacture
• Moderate aesthetics – depending on material and color match

Question 9

Advantages and disadvantages of monolithic zirconia crown:

Answer 9

Advantages:

• Very good aesthetics
• Control and stability of occlusion (fairly kind to opposing teeth)
• Durable (high fracture resistance)
• Near maximal preservation of tooth structure

Disadvantages:

• No true bonding (issue with longevity)
• Can be layered with porcelain but this leads to increased destruction of tooth structure

Question 10

phases of crown construction in the digital way:

Answer 10

1. Tooth preparation
2. Digital Impression
3. Design of prosthesis (crown) on software
4. Milling
5. Polishing and finishing

Question 11

phases of crown construction in the conventional way:

Answer 11

1. Toothpreparation
2. Impression
3. Construction of master cast and die
4. Manufactureofwaxpattern
5. Investmentofwaxpattern
6. Porcelain application
7. Polishing and Finishing

Question 12

Principles of crown preparation:

Answer 12

• Resistance form
• Retention form
• Marginal Integrity
• Preservation of the periodontium
• Structural durability
• Conservation of tooth tissue
• Aesthetics

Question 13

case assessment:

Answer 13

*You need to carry a full and thorough case assessment before proceeding to the crown preparation

• Caries risk Assessment
• Periodontal Assessment
• Occlusal examination
• Sensibility testing (response to EPT, Endofrost, Palpation testing, mobility)
• Periapical radiograph (x-ray image)
• Assess core (tooth structure)
• Diagnostic wax up (if indicated)
• Make sure you have a treatment plan

Question 14

steps of crown preparation:

Answer 14

1. Take shade of crown (if you will prepare for porcelain or zirconia)
2. Take two or three putty indices
3. Use local anesthetic if required
4. Prepare the tooth appropriately (use indices as guides)
5. Construction of temporary crown
6. Placement of retraction cord with haemostatic agent
7. Take impression
8. Place temporary crown
9. Check occlusion and adjust if needed
10. Complete records and laboratory card

Question 15

steps of crown cementation:

Answer 15

1. Check your lab work–check fit of crown on die, check shade
2. Remove temporary restoration
3. Clean the underlying prepared tooth
4. Try in the restoration
5. Check marginal fit(withprobe), contact points and occlusion
6. Check patient is happy with fit and appearance
7. Remove crown and clean both crown fit surface and fit surface of tooth. If
8. Indicated sandblast with Aluminium oxide 50μm
9. Cement with appropriate cement. Check and remove any excess cement. Also recheck occlusion